A Continuous Glucose Monitor (CGM) is a medical device that tracks glucose levels in body fluid every few minutes, providing real-time data on trends and patterns. This technology offers a significant advantage over traditional fingerstick testing, which only gives a single glucose reading at one moment. For most users in the United States, especially those managing diabetes with insulin, a prescription from a healthcare provider is required to obtain a CGM system. This requirement exists because the device is classified as a medical device requiring professional oversight for safe and accurate therapeutic use.
Why CGMs are Classified as Prescription Medical Devices
The prescription requirement for most Continuous Glucose Monitors stems from their classification by the U.S. Food and Drug Administration (FDA) as Class II medical devices. Class II devices are considered moderate-risk and require specific “special controls” to ensure safety and effectiveness. These controls include rigorous standards for clinical data to demonstrate accuracy, especially at high or low glucose levels.
CGM data is often used for making critical medical decisions, such as adjusting insulin doses. Inaccurate data or misinterpretation could lead to severe health consequences like hypoglycemia or hyperglycemia. The prescription process ensures the patient receives necessary medical guidance on how to insert the sensor and interpret the complex glucose data.
The FDA mandates that these prescription devices, often called integrated CGMs (iCGMs), meet strict performance requirements for accuracy. This high standard is necessary because iCGMs are designed to communicate with other connected devices, including automated insulin dosing systems. The prescription acts as a safeguard, linking the device’s therapeutic impact with a healthcare professional’s supervision.
The Patient Pathway to Obtaining a Prescription and Coverage
Obtaining a prescription-based CGM begins with a consultation with a healthcare provider, such as a primary care physician or an endocrinologist. The provider must establish medical necessity, which is the factor in securing both the prescription and insurance coverage. Common indications for coverage include a diagnosis of Type 1 diabetes or Type 2 diabetes managed with intensive insulin therapy, such as multiple daily injections or an insulin pump.
Since the devices and sensors are costly, insurance coverage is necessary for most people to gain access. Medicare and private carriers often require the patient to be on intensive insulin therapy and perform frequent self-monitoring of blood glucose. Insurers may also require a “prior authorization” process where the provider submits documentation proving the patient meets the necessary medical guidelines.
The prescription must be detailed to satisfy both clinical and insurance requirements, including the patient’s diagnosis code and the exact components needed. Depending on the plan, the CGM may be covered as a pharmacy benefit or classified as Durable Medical Equipment (DME). Classification as DME can involve different suppliers and paperwork, adding complexity to the process.
Patients who meet the medical necessity criteria often have low or zero out-of-pocket costs for their sensors, especially with manufacturer savings programs. If the patient does not meet the insurer’s specific requirements, the claim will likely be denied, requiring the patient to cover the full cost.
Over-the-Counter CGM Availability and Differences
While prescription models are the standard for therapeutic diabetes management, the market now includes over-the-counter (OTC) Continuous Glucose Monitors. These non-prescription devices are cleared by the FDA for direct consumer purchase. Their primary goal is general wellness, metabolic insight, and tracking the impact of diet and exercise on glucose levels.
OTC devices, such as Dexcom’s Stelo and Abbott’s Lingo, differ from prescription counterparts in intended use and safety features. Stelo is cleared for adults who do not use insulin and are not at risk for hypoglycemia. These non-prescription models often lack the real-time high or low glucose alerts that are standard on prescription devices and are lifesaving for insulin users.
The regulatory distinction means that OTC CGMs are not cleared for making immediate therapeutic decisions, such as insulin dosing adjustments. For example, Abbott’s Lingo is cleared as a general health and wellness tool and is not indicated for use by people with diabetes. For individuals managing complex conditions, the advanced features and safety alerts of the prescription-grade device remain medically necessary.